Boats, floating docks and other structures which remain relatively immobile and partially submerged beneath the surface of a body of water, whether salt water or fresh water, commonly accumulate a coating of material such as dirt and slime on their submerged surfaces. This coating is the result of a variety of fouling agents, but is predominantly caused by marine growth.
Among the marine life forms responsible for fouling boat hulls is the barnacle. Barnacles are totally sessile and most live attached to docks, shells, rocks, boat hulls and other submerged surfaces. When a boat is docked or anchored and immobile. barnacles are able to attach themselves to a boat's bottom when in the larval stage by secreting a cement like substance. Once the "cement" hardens, the barnacle becomes permanently attached to the boat hull and is extremely difficult to remove without damage to the hull's surface. Barnacles are particularly damaging to soft hull finishes, such as the gel coat normally present on fiberglass hulls. Although less damaging to the surface of the boat hull, algae and other marine organisms are also significant contributors to fouling.
The accumulation of marine growth and other fouling agents on a boat hull has a number of adverse consequences including significant increases in the cost of maintaining and operating a vessel. As described above, marine growth can cause extensive damage to paints, gel coats, and other substances used to treat and finish boat hulls. An accumulation of marine growth contributes to the process of osmotic blistering whereby the paint or gel coat on the submerged surface of the boat develops blisters and eventually forms pox exposing the hull to the environment. The hull surface must then be refinished. Also, the accumulation of marine growth on a boat hull has a marked effect on speed and fuel consumption. Barnacles can form encrustaceans on boat hulls that can reduce a boat's speed by 30% and cause a significant increase in fuel costs. Barnes, R. D., Invertebrate Zoology, 3d. ed. (1974). Algal growth has a similar effect on fuel consumption and speed.
Maintaining a clean hull surface will prolong the life of a boat and reduce the need for more expensive maintenance procedures. An effective method for removing fouling agents is to scrub the hull surface by hand; however, manually cleaning a boat hull is laborious, time consuming and inefficient.
The most effective way to clean a hull surface manually is to raise the boat from the water and then scrub the hull. Raising a boat from the water normally requires the availability of a lift and the opportunity to schedule use of the lift. This presupposes the proximity of a boat yard with a lift facility. It also requires the availability of space in the yard at which the vessel can be stored while the bottom cleaning takes place. Many boaters store their boats at marinas, private docks, or other locations which are not near boat yard facilities with lifts. Thus, hull cleaning in this fashion tends to be done at relatively long intervals between cleanings. This makes preventative maintenance, i.e., regular cleaning before the hull growth becomes problematic, unavailable as a practical matter.
The hull can also be cleaned manually by entering the water to scrub the hull but this method also has a number of difficulties associated therewith. First and foremost, it is often difficult to obtain any kind of purchase on the hull since the more the cleaner pushes on the hull in order to apply friction thereto, the more the cleaner is pushed away from the surface of the hull. Thus, it can get very tiring to be constantly propelling oneself, usually with the legs, in order to engage the surface of the boat. This can sometimes be alleviated by pushing off from the side of a dock or a dock piling. However, under many conditions of tidal flow and wave action, it is dangerous for a person to be in the water in the space between a boat and a dock because movement of the vessel toward the dock can pin the individual therebetween. Additionally, if the user is successful in pushing off on a dock piling or similar structure in order to obtain purchase on the boat hull, it is inconvenient and time consuming to have to reverse the position of the vessel between port alongside and starboard alongside in order to clean both sides of the hull. While it is possible to rig arrangements of ropes and the like which the individual in the water cleaning the hull can hold, these arrangements are cumbersome.
Entering the water to clean a boat hull presents a variety of other hazards as well. For example, in some areas of the United States it is illegal to enter the water around boat docks because of the risk of electrocution caused by cables in the water supplying shore power. In many instances it is unwise, even if legal. Additionally, as anyone who has ever cleaned a boat hull in the water knows, cleaning a reasonably fouled hull quickly leads to the act of swimming in murky and relatively unpleasant water. While it is customary to wear a diving mask during this activity, it can still become very difficult to see other parts of the hull and to continue the work because the loosened debris clouds the adjacent water. Naturally, if there are sufficient tidal currents or other water flow present to quickly remove this debris, it is difficult for the individual doing the cleaning to stay in the vicinity of the boat.
The fact that boats with overly developed bottom growths are virtually ubiquitous, particularly in the warmer climates of the southern United States, is testimony to the extent to which boaters will delay addressing the problem of bottom growth due to its significant inconvenience and expense. Furthermore, it should be noted that the difficulty of a bottom cleaning job increases geometrically with the time between cleanings. In other words, when the boat is allowed to sit twice as long under the same conditions, the cleaning job is normally more than twice as difficult and problematic. In particular, if a well developed set of barnacles gets attached to a hull, the removal of the barnacles will almost invariably damage the gel coat or varnish, whereas relatively easy regular cleaning at more closely spaced regular intervals could prevent the attachment of the barnacles to the hull in the first place, thus preventing damage to its finish.
To make the process of maintaining a clean hull more efficient and less laborious, a variety of different methods and mechanical devices have been developed which either prevent the accumulation of algae and barnacles or remove them from a boat's surface after accumulation. These devices and methods cause other problems in many instances and have been met with limited acceptance or have limited utility.
For example, one method currently available to prevent algal growth and the accumulation of barnacles on boat hulls is the application of a paint which contains a biocidal agent. Typically, this paint dissolves over time exposing fresh biocide on the surface of the hull. Generally, the paint lasts only a few seasons and must be reapplied. One advantage of this method is that the surface of the paint becomes smoother as the paint dissolves, as opposed to other paints which tend to blister and develop pox. The disadvantage is that the biocidal paints are expensive and that this particular method requires that the boat be dry docked for prolonged periods of time to repaint its surface. Additional problems of environmental and regulatory nature also result: from the use of biocidal paints. Some jurisdictions are outlawing their use in inland waters and there is concern that leeching of biocides in coastal areas near wetlands can damage oyster beds and shrimp spawning grounds.
A variety of mechanical boat hull cleaning devices have been designed to ease the task of hull maintenance. U.S. Pat. No. 4,204,494 to Bridwell et al. discloses a boat washing apparatus having a stationary frame to which are pivoted a pair of carrier frames with journal rotary power driven brushes across which an elevated boat mounted on a support may be moved. Although the device disclosed by Bridwell et al. is commonly used and considered to be effective for removing marine growth, it requires a professional operator. As with manual cleaning, it also requires that the boat be lifted from the water and to the place where the cleaning device is located. This is an expensive and time consuming process that is suitable for periodic major cleaning but is impractical for keeping the hull continually free of marine growth.
A hull cleaning device which does not require that a boat be removed from the water is disclosed in U.S. Pat. No. 4.395,966 to Murphy. Murphy discloses a boat hull scrubber which allows the boat to remain afloat and the person cleaning the boat to remain aboard. This makes it possible to clean the boat in open water. Murphy discloses a boat hull scrubber comprising a one piece belt of fibrous abrasive material with a plurality of floats mounted along the undersurface of the belt such that the floats pivot at fight angles to the belt. The hull cleaner is designed such that the floats urge the belt into contact with the hull of the boat when the cleaning strap is drawn beneath the boat. As the operators on the deck of the boat pull either end of the cleaning strap, the strap is forced into frictional contact with boat hull.
In practice, the device disclosed in the patent to Murphy has several deficiencies. For one, the large number of floats attached to the full length cleaning pad and necessary to keep the cleaning pad afloat, occupy significant storage space on board a vessel. This makes it impractical to travel with the scrubber or to stow it on board. On most recreational boats, storage space is scarce and a bulky rarely used item, particularly one which is not a piece of essential safety equipment, will rarely be stowed on board. The great number of floats needed to keep the cleaning pad afloat also makes it difficult to pull the floats and pad beneath the surface of the water and to position them beneath the hull of the boat. Furthermore, the relatively large buoyancy of this device can cause it to creep toward the bow of the boat when trying to clean the sloped portion of the hull between the bow and the keel. In other words, the device is hard to get under the boat and difficult to control.
The Murphy patent exhibits several other deficiencies as well. For example, the force required to to pull the scrubbing pad back and forth across the hull tends to create tension along the length of the scrubbing pad. This tension counteracts the intended upward pressure of the floats and causes the scrubbing pad to pull away from the surface of the hull. Thus, the effectiveness of the device is reduced. Additionally, because the Murphy hull scrubber uses a full length scrubbing belt, the friction created between the scrubbing belt and the hull of the boat makes it difficult to move the device. It requires a great amount of energy, causing the individuals operating the device to tire quickly. The friction created along the length of the pad may also cause the boat to roll from side to side as the operators go through the scrubbing motion, tending to put the scrubbing individuals in the water. Finally, the Murphy device is not adaptable to different marine environments because the cleaning pad itself is an integral and permanent pan of the device. This eliminates the possibility of using alternate or replacement cleaning pads. If the belt is damaged or the cleaning pad is worn, the entire device must be replaced.
A variety of simpler and inexpensive mechanical boat cleaning devices have been developed and abound on the market. For example, currently on the market is a device which comprises a scrubbing pad attached to the end of a pole which may be extended into the water by a person standing on a dock. The person then scrubs up and down in an attempt to remove the marine growth. This technique is not particularly effective because it is difficult to apply sufficient pressure to remove the marine growth. Additionally, it does not allow access to all sides of the boat and does not allow the scrubber to reach the underside of the hull. Generally, the methods and devices currently available have limited utility and fail to solve the problems in the art.
Thus, what is needed in the art is a boat hull cleaning device which is relatively inexpensive, portable and compact; which can be operated by the boat owner; and which allows the operators to remain on board and the boat afloat during the cleaning process.